Asthma gene breakthrough

Previously, researchers thought up to 30 genes could be behind the disease, which affects 3.4 million people in Britain and 150 million worldwide.

The latest finding will make it far easier to create new drugs for treating the condition and devise a screening test.

The research, funded by the Medical Research Council and drug giant Schering-Plough, was carried out by scientists at Southampton University and U.S. company Genome Therapeutics.

They were 'astonished and heartened' by the finding, which 'gives lie' to the orthodox idea that diseases such as asthma have very complex causes.

'In the 25 years since I have been doing asthma research this is the biggest discovery that's been made,' said Dr Stephen Holgate, one of Britain's leading asthma experts, who led the research.

'It's going to change the whole way we look at the disease.'

Dr Holgate's team had been screening British families for an asthma gene and found five potential candidates.

They linked up with Schering and Genome Therapeutics, which had fast genetic screening tests, and homed in on one gene first. 'This gene was very, very strongly linked to asthma - like a million to one,' explained Dr Holgate.

'That was a big surprise. Usually with a complex disease there are many genes with a small contribution, but this is a major gene.

'It could account for 40 per cent of clinical presentations (cases of asthma).'

Dr Holgate added: 'I would have thought there were ten or 15, maybe 20 genes, all giving five per cent, and then some influence of the environment as well.

'What shocked me is that there is this one gene that seems to stand out so remarkably.'

He declined to name the gene, but said it was involved in lung function.